Coarse-grained strain dynamics and backwards/forwards dispersion

A Particle Tracking Velocimetry experiment has been performed in a turbulent flow at intermediate Reynolds number. We present experimentally obtained stretching rates for particle pairs in the inertial range. When compensated by a characteristic time scale for coarse-grained strain we observe constant stretching. This indicates that the process of material line stretching taking place in the viscous subrange has its counterpart in the inertial subrange. We investigate both forwards and backwards dispersion. We find a faster backwards stretching and relate it to the problem of relative dispersion and its time asymmetry.Comment: 13 pages, 7 figue

Social Dilemmas and Cooperation in Complex Networks

In this paper we extend the investigation of cooperation in some classical evolutionary games on populations were the network of interactions among individuals is of the scale-free type. We show that the update rule, the payoff computation and, to some extent the timing of the operations, have a marked influence on the transient dynamics and on the amount of cooperation that can be established at equilibrium. We also study the dynamical behavior of the populations and their evolutionary stability.Comment: 12 pages, 7 figures. to appea

Evolution of Cooperation and Coordination in a Dynamically Networked Society

Situations of conflict giving rise to social dilemmas are widespread in society and game theory is one major way in which they can be investigated. Starting from the observation that individuals in society interact through networks of acquaintances, we model the co-evolution of the agents' strategies and of the social network itself using two prototypical games, the Prisoner's Dilemma and the Stag Hunt. Allowing agents to dismiss ties and establish new ones, we find that cooperation and coordination can be achieved through the self-organization of the social network, a result that is non-trivial, especially in the Prisoner's Dilemma case. The evolution and stability of cooperation implies the condensation of agents exploiting particular game strategies into strong and stable clusters which are more densely connected, even in the more difficult case of the Prisoner's Dilemma.Comment: 18 pages, 14 figures. to appea

Validation of the French Version of the "Patterns of Activity Measure" in Patients with Chronic Musculoskeletal Pain.

Background. The "Patterns of Activity Measure" (POAM-P) is a self-administered questionnaire that assesses "avoidance", "pacing" and "overdoing" activity patterns in chronic pain patients. Objectives. To adapt the POAM-P to French ("POAM-P/F") and test its validity and reliability in Chronic Musculo-Skeletal Pain patients (CMSP). Methods. We followed the recommended procedure for translation of questionnaires. Five hundred and ninety five inpatients, admitted to a tertiary rehab center in the French-speaking part of Switzerland for chronic pain after orthopedic trauma, were included (sex ratio M/F = 4.36, mean age 43 ± 12). Face, content and criterion validities, internal consistency and reliability were assessed. Data included: TAMPA Scale for Kinesiophobia (TSK), Chronic Pain Coping Inventory (CPCI), Pain Catastrophizing Scale (PCS), Brief Pain Inventory (BPI), Hospital Anxiety and Depression Scale (HADS). Results. Face and content validities were checked during the translation process. Correlations between POAM-P/F-avoidance and TSK, POAM-P/F-pacing and CPCI-pacing, POAM-P/F-overdoing and CPCI-task persistence were highly significant (r > 0.3, p < 10(-2)). The three subscales demonstrated excellent homogeneity (Cronbach's alpha coefficients > 0.8) and test-retest reliability (Intraclass Correlation Coefficients > 0.8). They correlated very differently with the other scales. Discussion and Conclusion. The three POAM-P/F subscales clearly assess different behaviors in CMSP. The POAM-P/F is a suitable questionnaire for classifying French speaking CMSP into avoiders, pacers or overdoers

Evaluation of a population-based prevention program against influenza among Swiss elderly people.

Influenza is a major cause of morbidity and mortality and occurs in epidemics in the winter. This study is an evaluation of a population-based prevention program against Influenza, implemented during autumn 2000 by the Health Department of the Canton of Vaud. A pre-intervention/post-intervention design was used. In June 2000 and March 2001, 4007 questionnaires were sent to two different stratified random samples of people aged 65 and over living in the Canton of Vaud, Switzerland. Univariate, bivariate and multivariate analyses were performed. Vaccination coverage among people older than 65 was 58.0% in 1999 (95% CI: 56.2%-59.8%) and 58.4% (95% CI: 56.6%-60.2%) in 2000. A 6.5% significant increase in vaccination coverage was seen in the group of people aged 65 to 69 (p = 0.008). In the pre-intervention survey immunisation rates were 22.6% among people who had not consulted a physician, 59.2% among those who had consulted a physician once, and 73.2% among those who consulted twice or more (p = 0.001). These rates were respectively 30.8%, 58.0% and 75.1% (p = 0.001) in the post-intervention survey. No global increase in Influenza vaccination coverage in the elderly population could be observed following a community based intervention in a Swiss Canton. However, the enhanced vaccination rates noted in the 65-69 years old group and in people who did not receive medical care are compatible with an effect of the campaign. Further increase in vaccination coverage may be obtained by diversification and repetition of such promotion campaigns

A new ambulatory system for comparative evaluation of the three-dimensional knee kinematics, applied to anterior cruciate ligament injuries

The aim of this study was to develop an ambulatory system for the three-dimensional (3D) knee kinematics evaluation, which can be used outside a laboratory during long-term monitoring. In order to show the efficacy of this ambulatory system, knee function was analysed using this system, after an anterior cruciate ligament (ACL) lesion, and after reconstructive surgery. The proposed system was composed of two 3D gyroscopes, fixed on the shank and on the thigh, and a portable data logger for signal recording. The measured parameters were the 3D mean range of motion (ROM) and the healthy knee was used as control. The precision of this system was first assessed using an ultrasound reference system. The repeatability was also estimated. A clinical study was then performed on five unilateral ACL-deficient men (range: 19-36years) prior to, and a year after the surgery. The patients were evaluated with the IKDC score and the kinematics measurements were carried out on a 30m walking trial. The precision in comparison with the reference system was 4.4°, 2.7° and 4.2° for flexion-extension, internal-external rotation, and abduction-adduction, respectively. The repeatability of the results for the three directions was 0.8°, 0.7° and 1.8°. The averaged ROM of the five patients' healthy knee were 70.1° [standard deviation (SD) 5.8°], 24.0° (SD 3.0°) and 12.0° (SD 6.3°) for flexion-extension, internal-external rotation and abduction-adduction before surgery, and 76.5° (SD 4.1°), 21.7° (SD 4.9°) and 10.2° (SD 4.6°) 1year following the reconstruction. The results for the pathologic knee were 64.5° (SD 6.9°), 20.6° (SD 4.0°) and 19.7° (8.2°) during the first evaluation, and 72.3° (SD 2.4°), 25.8° (SD 6.4°) and 12.4° (SD 2.3°) during the second one. The performance of the system enabled us to detect knee function modifications in the sagittal and transverse plane. Prior to the reconstruction, the ROM of the injured knee was lower in flexion-extension and internal-external rotation in comparison with the controlateral knee. One year after the surgery, four patients were classified normal (A) and one almost normal (B), according to the IKDC score, and changes in the kinematics of the five patients remained: lower flexion-extension ROM and higher internal-external rotation ROM in comparison with the controlateral knee. The 3D kinematics was changed after an ACL lesion and remained altered one year after the surger

Variations in quality of care for heart failure.

BACKGROUND: The objective of our study was to assess hospital-to-hospital variations for the management and treatment of heart failure (HF) patients. METHODS: We performed a cross-sectional study among randomly selected patients with ICD-10 (International Classification of Disease, 10th revision) HF hospitalised in three Swiss university hospitals in 1999. Demographic characteristics, risk factors, symptoms and findings at admission and discharge medications were abstracted. The main outcome measure was the percentage of patients receiving appropriate management and treatment as defined by quality of care indicators derived from evidence-based guidelines. Quality indicators were considered only when they could be applied (no contra-indications). RESULTS: Among 1153 eligible patients with HF the mean age (SD) was 75.3 (12.7), 54.3% were male. Among potential candidates for specific interventions left ventricular function (LVF) was determined in 68.5% of patients; 53.8% received target dose of angiotensin converting enzyme inhibitors (ACEI), 86.0% any dose of angiotensin receptor blockers; 21.9% b-blockers, and 62.1% anticoagulants at discharge. Compared to hospital B (reference), the adjusted odds ratios (OR) (95% CI) for LVF not determined were 3.82 (2.50 to 5.85) in hospital A and 3.25 (1.78 to 5.93) in hospital C. The adjusted OR (95% CI) for not receiving target dose ACEI was 1.76 (0.95 to 3.26) for hospital A and 3.20 (1.34 to 7.65) for hospital C compared to hospital B. CONCLUSIONS: Apparently, important hospital-to-hospital variations in the quality of care given to patients with HF could have existed between three academic medical centers

Quality of health care surveillance systems: review and implementation in the Swiss setting.

Quality of health care has been a subject of attention for many years in the USA and in Europe. Since the introduction of the new federal law on insurance in 1996 it has evolved to a progressively more important issue within the Swiss health care system. In this review, some theoretical concepts of quality of health care, variations, and surveillance systems are explored. Examples of quality of health care surveillance systems that have been developed successfully in the USA, in Canada, in Australia, and in Europe are discussed. They all demonstrate the interest in creating a large range of quality indicators in the surveillance system and in evaluating hospital performance using a benchmark approach. Currently, the measurement of quality with appropriate indicators is a subject of intense debate between the Swiss Hospitals Association (H+) and the Swiss Health Insurance Consortium (Santésuisse). Examples of existing surveillance systems in Switzerland are the Outcome Verein in Zurich and the quality of care program of the Canton of Valais. The FoQual association has also contributed to the debate by reviewing six indicators, which could be used nationally for a healthcare surveillance system. In this debate it is important to stress that ideal quality indicators intended for use as measures of quality in Swiss hospitals need to be both appropriate and valid. Only indicators that fulfil these conditions should be integrated in a Swiss health care surveillance system. Priority needs to be given to quality indicators and methods with the highest level of evidence and with a solid scientific basis

Avoidance, pacing, or persistence in multidisciplinary functional rehabilitation for chronic musculoskeletal pain: An observational study with cross-sectional and longitudinal analyses.

Three main activity patterns have been distinguished in describing chronic pain (avoidance, pacing and persistence). However, their influence on patient outcomes remains a question of debate. This observational study aimed to measure the associations between the avoidance, pacing, and persistence (labelled overdoing) scales of the Patterns of Activity Measure-Pain (POAM-P), self-reported outcomes (pain-interference, depression, functional ability), and observational outcomes (walking, lifting test, physical fitness). We conducted an observational study with cross-sectional and longitudinal analyses. The data were collected prospectively before and after treatment, which was a 5-week functional rehabilitation including vocational aspects. In addition to self-reported and observational outcomes, patients were asked if they thought they would be able to return to work at 6 months. Analyses were conducted with treatment effect sizes, correlations, and multiple regression models. In this sample (891 patients), we found on average small to moderate improvements for pain-interference and observational outcomes (Cohen's d: 0.37 to 0.64). According to the multivariable models, overdoing was associated with most of the beneficial psychosocial and observational outcomes (β -0.13 to 0.17; all p<0.01). Avoidance was related to negative psychosocial outcomes before treatment (β -0.09 to 0.17; all p<0.015). Pacing, which had moderate correlation with avoidance (r = 0.46), was not associated with most of the outcomes. The feeling that the goal of returning to work was attainable was associated with lower avoidance scores (adjusted OR 0.97; p = 0.024). The overdoing POAM-P scale probably measures a task-contingent persistence, which appears appropriate in the setting of this study. Persistent behavior was indeed related to small or moderate positive biopsychosocial outcomes, before and after treatment. Moreover feeling able to return to work was related to lower avoidance. Further studies should test the efficacy of motivational strategies that may promote functional task-contingent persistence and reduce avoidance of painful tasks

The self-assessment INTERMED predicts healthcare and social costs of orthopaedic trauma patients with persistent impairments.

To use the self-assessment INTERMED questionnaire to determine the relationship between biopsychosocial complexity and healthcare and social costs of patients after orthopaedic trauma. Secondary prospective analysis based on the validation study cohort of the self-assessment INTERMED questionnaire. Inpatients orthopaedic rehabilitation with vocational aspects. In total, 136 patients with chronic pain and impairments were included in this study: mean (SD) age, 42.6 (10.7) years; 116 men, with moderate pain intensity (51/100); suffering from upper (n = 55), lower-limb (n = 51) or spine (n = 30) pain after orthopaedic trauma; with minor or moderate injury severity (severe injury for 25). Biopsychosocial complexity, assessed with the self-assessment INTERMED questionnaire, and other confounding variables collected prospectively during rehabilitation. Outcome measures (healthcare costs, loss of wage costs and time for fitness-to-work) were collected through insurance files after case settlements. Linear multiple regression models adjusted for age, gender, pain, trauma severity, education and employment contract were performed to measure the influence of biopsychosocial complexity on the three outcome variables. High-cost patients were older (+3.6 years) and more anxious (9.0 vs 7.3 points at HADS-A), came later to rehabilitation (+105 days), and showed higher biopsychosocial complexity (+3.2 points). After adjustment, biopsychosocial complexity was significantly associated with healthcare (ß = 0.02; P = 0.003; exp <sup>ß</sup> = 1.02) and social costs (ß = 0.03; P = 0.006, exp <sup>ß</sup> = 1.03) and duration before fitness-to-work (ß = 0.04; P < 0.001, exp <sup>ß</sup> = 1.04). Biopsychosocial complexity assessed with the self-assessment INTERMED questionnaire is associated with higher healthcare and social costs